Emission control testing of automobiles, and similar vehicles, has come under increased scrutiny due to the discovery that the Engine Control Unit (ECU) of certain automobiles was altered to circumvent tests designed to ensure clean engine emissions. In certain cases, a defeat device had been used to change a vehicle's performance during testing to be different than when the vehicle was used in “real-world” conditions (e.g., the intended daily usage pattern of the end consumer of the vehicle).
A defeat device is an auxiliary emission control device that reduces the effectiveness of the emission control system under conditions, which may reasonably be expected to be encountered in normal vehicle operation. The use of defeat devices has resulted in substantial fines to car manufacturers, exceeding a billion dollars in addition to a loss in consumer confidence. Hence, there is a significant economic incentive for car manufacturers to prevent and deter the use of defeat devices by their suppliers, and various departments of the car manufacturer itself.
Conversely, the pressure to use defeat devices is very high, because in many cases, the cars could only pass environmental acceptance and/or on-going period tests when the defeat devices were used. It is in the interest of car manufacturers to enable certification authorities to detect these defeat devices in a manner that restores consumer confidence, and continues to remain effective while defeat devices adapt in methods and sophistication.